As the years passed to a decade, and the ships of Earth rode to Mars and Venus, it began to be apparent that a lifetime of space travel meant a hideous death. Scientists attributed it to the cosmic rays, for out in space there was no blanketing layer of atmosphere to protect the fleshy tissues of man from their piercing power. It had long been a theory that cosmic rays were related to the birth of new life in the cosmos; perhaps they were, said some, the direct cause of life. Thus by causing the unorderly growth of new cells that man called cancer, the cosmic rays were destroying the life they had created. It meant death to travel in space, and only the stupendous fees paid to the young men who believed in a short life and a merry one, kept the ships plying between Mars and Earth and Venus. Lead kept out the cosmic rays, but lead would not stand the terrific speed required to lift a craft free of planetary gravity; and an inner coating of lead brought men into port raving with lead poisoning illusions. Cancer cases increased on Earth. It was learned that the virulent form of space cancer, as it was called, was in some peculiar manner, contagious to a certain extent. The alarm spread. Men who voyaged in space were segregated, but the damage had been done. The Plague spread, and ravaged the peoples of three planets. Hospitals were set up, and precious radium used for the fight. But the radium was hard to come by. There was just not enough for the job. A ship was built, the fastest vessel ever made by man. It was designed for speed. It made the swiftest interplanetary craft seem a lumbering barge by comparison. And mankind gave it to Valentine Emerson to take it out among the stars to find the precious radium in sufficient quantities to halt the Plague. It had not been easy to find a crew. The three worlds knew the men were going to their doom. It would be a miracle if ever they reached a single planet, if they did not perish of space cancer before their first goal. Carson Nichols, whose wife and children were dying of the Plague, begged him for a chance. A murderer convicted to the Martian salt mines, Karl Mussdorf, grudgingly agreed to go along on the promise that he won a pardon if he ever came back. With Mussdorf went a little, wry-faced man named Tilford Gunn, who knew radio, cookery, and the fine art of pocket-picking. The two seemed inseparable. Now Emerson was breathing softly, "Yes, it had better be there, or else we die." He ran quivering fingers over his forearm, felt the strange lumps that heralded cancer. Involuntarily, he shuddered. Steps clanged on the metal runway beneath them. Mussdorf pushed up through the trap and got to his feet. He was as big as Emerson, bulky where Emerson was lithe, granite where Emerson was chiseled steel. His hair was black, and his brows shaggy. A stubborn jaw shot out under thin, hard lips. "There it is, Karl," said Nichols. "Start hoping." Mussdorf scowled darkly, and spat.